The goal of the UCLA-CGEP is to identify novel pathogenic mechanisms of sporadic PD based on understanding the critical cellular pathways disrupted by Putative Environmental Toxicants (PETs). This group found associations between high levels of exposure to PETs with PD, and in parallel experiments discovered PETs alter specific cellular pathways potentially involved in disease pathogenesis, the ubiquitin-proteasome system (UPS), microtubule polymerization, and aldehyde dehydrogenase (ALDH). The goal of this project is to determine the relative importance of UPS disruption (especially E1 activating enzyme), microtubules and ALDH by candidate pesticides in conferring vulnerability to dopamine (DA) neurons using cell-based assays. We will test whether disruption of these cellular mechanisms in isolation or in combination (i.e., multiple hits) leads to nigrostriatal cell death using cell lines and primary mesencephalic neurons in culture. A secondary goal of this project is to determine whether selective vulnerability of nigral neurons is due, at least in part, to alterations in DA homeostasis by measuring the effect of PET exposure on DA and its metabolites and altering cytosolic DA using viral mediated VMAT expression. A third goal is to identify additional agricultural pesticides that are also able to disrupt those same cellular pathways shown to alter the viability of nigrostriatal dopaminergic neurons. These studies will help elucidate the mechanisms of action of agents known to increase PD risks over long periods of exposure. The results will also help determine which genetic polymorphisms associated with Project 4, and the screening results will guide further epidemiological analyses of agricultural risk factors. The hypothesis is that the determination of mechanisms of action of environmental agents that increase the risk of PD will shed light on the pathophysiological processes involved in sporadic PD.